A through switch connection in an ATM network element or ATM switch in a telecommunication network is composed of legs and a leg connector. The through switch connection means all the connections and resources between physical endpoints at external interfaces. A leg control feature is required to manage necessary connections for incoming and outgoing calls of the through switch connection. Typically, a leg consists of several services and subconnections between them. The legs are connected by a leg connector.
The services are provided by an ATM adaptation layer 2 (AAL2) connection control, and the subconnections are handled by an ATM connection control. Conventionally, leg control and connection control (AAL2 connection control and ATM connection control) provide each leg consisting of AAL2 services and subconnections in several parts. Furthermore, the services and subconnections have to be accepted by a connection admission control. The accepting process is also done in pieces. According to FIG. 1, the leg control asks the control comprising the ATM connection control and the AAL2 connection control to establish the services and subconnections. The ATM connection control and the AAL2 connection control in turn ask the connection admission control for acceptance for the services and subconnections.
However, this conventional way of providing connection admission control is ineffective since many messages have to be exchanged in order to accept each connection being part of a leg. Moreover, when connection admission control accepts for example an AAL2 connection, this does not mean that the other connections forming the leg are acceptable by the connection admission control. Thus, the conventional connection admission procedure is both ineffective and conceptually difficult.